Field of Invention
The present invention relates generally to fastening devices and, more particularly, to a device for securing a number of sheets of paper together in a neat and orderly fashion.
It is well known in the art to fasten several sheets of paper together in a stack to form a document which can range from a couple of pages to many hundreds.
Numerous types of paper fastening devices have been disclosed in the prior art. For example, the common paperclip available in different sizes can be utilized to secure several sheets of paper together. However, the individual paper sheets are easily displaced during handling which disrupts the neatness of the document.
Many files and documents have more numerous pages. For example, 10 to 50 sheets of paper or more can be fastened together in a removable manner by the use of high tension binder clips and spring clips such as ACCO Binder Clips. However, such devices have several disadvantages. Most of the binder clips require lever handles to obtain enough leverage to open the high tension jaws of the clamp mechanism. Such lever handles can be difficult to use and cause the secured document to have a bulky profile.
Further, in order to accommodate a variable number of sheets, the jaws of most binder clips grab a thin stack at a sharply oblique angle thereby presenting a very narrow binding surface to the paper. Because the effective binding surface of these devices is quite narrow, they leave a deformation on the surface of the paper. Thus, the sheets near the top and bottom of the stack frequently tear at the site of binding when the document is placed between other documents in the file because these sheets tend to slide laterally from the stack and against the narrow binding surface of the clip.
So-called corner fasteners are also known in the prior art. For example, U.S. Pat. No. 5,212,850 discloses a device for holding several sheets of paper together at the corner of the stack. However, the number of sheets that can be successfully bound by full contact with the binding faces thereof is limited by the width of the hinge and the clasp. When such a device is applied to a stack that is thinner than the width of the hinge, the papers in the stack tend to slip and the top and bottom sheets are creased and subject to tearing. In addition the opening and closing of the fastener requires the manipulation of two separate clasps to secure or release the paper stack.
In view of the problems described above, there is need for a paper fastener capable of accommodating paper stacks of various thicknesses that is simple to operate and conforms to the shape of the paper stack to provide a low profile for storage. Further, it is desirable to provide a paper fastener wherein the stack of papers to be secured is utilized to pry open the clamping mechanism thereby eliminating the levering arms which form a part of conventional binder clips.